Homeostasis and Cardiovascular System

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The American physiologist Walter Cannon used the term Homeostasis to describe the body’s ability to maintain a constant stable internal environment despite the changes to the external surrounding1,2. The body has a range of receptors these are used to constantly monitor the body’s internal conditions to keep them in physiological limits. To achieve this, every organ works together and thus the body works together as a whole. This requires body to communicate with the organs, this is established through two very highly specialized systems; nervous system and endocrine system, they use electrical impulses and hormones to communicate respectively1. It is vital for our body to maintain homeostasis for our survival, this ability of the body allows us to adapt to our environment which is why we can live in a variety of different settings3.

The mechanism of every homeostatic control has three interdependent components; the receptor, which is a sensor that responds to a change (stimuli) in the environment, by sending information through the afferent pathway to the control center1. The second component, which is the control center, is where the information received is assessed and it is determined whether the conditions are in limits1. The final component is the effector; it uses the information provided by the control center to respond to the change1. The information travels along the efferent pathway from control center to the effector this result in a response to the stimuli1.

There are two different homeostatic mechanisms; a negative feedback and a positive feedback. Which mechanism is in action depends on the stimuli. During negative feedback the mechanism reacts by producing a response to the variable in opposite directions, this is achieved through reducing the intensity or cutting off the output completely2. For example, you have your central heating on but you open your window this would result in losing heat hence, reducing the temperature of the room. This change would be detected by the thermostat thus signals will be sent to the boiler to increase the activity. This increase in activity would lead to restoring of the temperature. Now if you close the window and the temperature is established the thermostat would detect this and so will again send signals to the boiler to reduce the activity.

For the positive feedback mechanism the body tends to produce a response that increases the activity of the variable so it supports the change1,2. This moves the stimulus further away from its physiological range. This type of control is not as common as the negative control; it has no limits and is more focused on continuous change1. It occurs during the events where frequent adjustment is not required. A very good example for this control is blood clotting. If a blood vessel is damaged, the platelets tend to stick to the site and release chemicals which attract more platelets1. This leads to a rapid accumulation of platelets which eventually forms a clot.

The cardiovascular system consists of the heart and the blood vessels. Its job is to pump the blood to all parts of the body. The system contributes to maintain homeostasis in the body at all times whether it’s to do with providing brain cells with oxygen and glucose so that the control center in the brain carry’s on working to its best potential or working with kidneys to control the blood volume. The system itself is very complex and specialized.

The blood flow in the body must be kept constant and steady. This requires the body to work as a whole with the heart being the center of the homeostatic control. The components that control blood pressure in the heart play a significant role in homeostasis. Cardiac output (CO), Stroke volume, peripheral resistance, blood volume and heart rate all of these contribute towards regulating blood pressure in the body4. The cardiac output “is the volume of blood pumped put by each ventricle in 1 minute”5 . It can be measured...
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